The present invention relates to a security card, such as a credit card or identification card. A principal objective of a security card is that it cannot be easily modified or reproduced, and in particular that it cannot be modified or reproduced in such a way that the modification or reproduction, even if not perfect, is usable in place of the original. For example, if a fake credit card is sufficiently authentic-looking as to be accepted by a store clerk, it matters little that a skilled person can distinguish it from the genuine article.
In the past, distinctive graphics and embossings, as well as magnetic characters, were used on cards for security and verification purposes. These means, however, have posed little problem for the unscrupulous, with the result that millions of dollars are lost annually due to fraudulent card use. Even the relatively recent use of a small holograph on the card has not solved the problem.
Another known class of security-type cards employs a machine readable code. These cards contain predetermined optical refractors, which result in a positive identification when the card is inserted into the corresponding machine-reading apparatus. While systems such as these are perhaps more secure than the conventional credit-type card, they are prohibitively expensive and complex and require that the card be used with a reading apparatus specifically tailored to its coding system, thus reducing flexibility. In addition, the stored data is machine-readable only, which further limits the system's utility.
The present invention seeks to overcome these shortcomings by providing a simple, inexpensive and tamper-proof card which is readable by both human and machine means. Moreover, the present invention provides a security card which is virtually incapable of being reproduced or modified in any reasonably acceptable manner.